Are Green Plastics Really ‘Green’?
Bioplastic, biodegradable, plant-based, recyclable, and compostable are popular terms on single use plastic products and packaging. While these green marketing words sound good, clarity is needed to understand the flood of new plastic products. Often used interchangeably and in combination with each other, these terms have very different meanings. “Bioplastic” and “plant-based” indicate the source materials used to make the plastics. “Biodegradable,” “recyclable,” and “compostable” describe possible options after use.
Plant-based, Bio-based, or Bioplastic:
Plant-based, Bio-based, or Bioplastic identifies particular details about the production of the plastic. Bio- or plant- prefixes mean that a certain percentage of the chemicals (or chemical feedstock) used to make the plastic were derived from renewable resources like corn, sugarcane, soy, bacteria, or cellulose. The percentages can vary from a few percent to 100 percent. Often, renewables are used to generate identical polymers compared to those derived from petroleum, the traditional and main source of plastic polymers. In other words, with a bio-based label, the plastic that hits the market can be chemically and/or physically indistinguishable from petroleum-derived plastic. Even though there are new and novel bio-based plastic polymers, and they are chemically different, the important thing to remember is that bio-based plastics may or may not be better for the environment
than petroleum plastic.
Several authoritative bodies set guidelines for green plastics. In the US, the American Society for Testing and Materials (ASTM) and the Federal Trade Commission (FTC) both provide definitions for biodegradable plastics. According to the FTC, in order to label plastic as biodegradable, there must be scientific evidence that the plastic completely breaks down into its elements in a reasonable amount of time. The definition provided by ASTM is a bit tighter. It defines biodegradation as degradation of the chemical structure of the plastic by naturally-occurring microorganisms. Important specifics missing from established guidelines are the time frame (days to thousands of years), conditions (aerobic, anaerobic, ambient temperatures or 50 to 60°C), and location (beach, backyard, landfill, or industrial composter).
Nearly everything will eventually degrade and can theoretically be eaten by microbes. In the case of plastics, it could take thousands of years if left in the environment. Therefore, the term biodegradable is so loose that it can mean anything.
A slightly more transparent designation for plastics is compostable. Composting is the process by which biodegradation occurs. Like any process, there are conditions that must be met and these conditions are not found in your backyard compost pile. The ASTM D6400 specification defines compostable for plastics as mineralization to carbon dioxide and water in 180 days or less in an industrial aerobic composting facility. In such a facility, the temperature, air content, moisture, acidity, and carbon/nitrogen ratio are tightly controlled through industrial processes. It is under these precise conditions that compostable plastics are biodegraded. There is a certifying body called Biodegradable Products Institute (BPI, www.bpiworld.com) that reviews products and will grant the use of BPI’s compostable logo on the product if it meets ASTM D6400. For products without a certified BPI logo, the word compostable is unsubstantiated. Products that are compostable have different chemistries than traditional plastics and cannot be recycled, even though they may be inaccurately labeled as such. Finally, even though a plastic is compostable, it does not mean that it will become a soil nutrient.
Similar to the other green terms, the recyclable term is complicated. Recyclable means that the plastic goes through a long process of collection, separation by resin code (#1-7), chipping or shredding, washing, and melting. The reformed plastic is almost never the same product. Plastic bottles get recycled into park benches and fleece jackets but not back into plastic bottles.
There are issues with recycling plastic. First, it is hard to tell if a plastic is recyclable. The chasing arrows symbol adopted by the US Plastics Trade Association (SPI) in 1988 was never intended to mean that plastics #1-7 are actually recyclable. The chasing arrows symbol stamped on the bottoms of plastic was simply selected to indicate the resin (or polymer) type.
Not all plastics are well suited for re-melting and reforming due to their chemical structure.
Secondly, it is impossible to know whether the plastic tossed into the bin will be recycled. The plastics that can be recycled seldom are recycled for any of the following reasons: 1) it may be cheaper to make a product from virgin materials, 2) there might not be a market (supply and demand arguments), 3) it may be more cost effective to landfill it, and 4) contaminants often ruin the melt yielding brittle and unusable plastic products. Basically, plastic is difficult to recycle and it can be cost-prohibitive. The result is a national recycling average of around nine percent of yearly plastic production. A 2011 waste characterization study conducted for the Humboldt Waste Management Authority reported 12.5 percent of Humboldt County’s waste is plastic.
What can a responsible consumer do to crack the green plastic marketing code? Since the plastics industry is ever-growing and highly adaptive, even the most informed consumer is scrambling to keep up. The question Zero Waste Humboldt urges us to ask is: “What are the alternatives to single use plastics that I can adopt in my daily life?” A solution: bring your own reusable glass, ceramic, or metal cup, mug, and to-go container. Keep cutlery and dishes in your office, in your bike bag, etc. If you are caught hungry or thirsty without your reusable food/beverage container and have to purchase a plastic product, then keep it, wash it, and re-use it many times. Especially in California’s remote, rural Redwood Coast where industrial compost facilities and recycled plastics manufacturers are scarce or far away, a shift from single use plastics to reusable food and beverage containers is essential.
Choose to Reuse!
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